Positive retention of a parked vehicle against a loading dock during loading and unloading thereof is essential from a safety standpoint. Heretofore, attempts at effecting such retention were to either rely merely on the brakes of the vehicle per se; utilize blocks which were wedged between the roadway on which the vehicle was parked and the front side of a pair of the vehicle wheels; or use of retaining chains or cables secured between the vehicle and a portion of the loading dock. Each of the aforegoing means were oftentimes ineffective because (1) the brakes were not properly set; (2) the blocks became lost or the roadway surface was slippery; or (3) the chain or cable was ignored because it was awkward, time-consuming, and required an inordinate amount of manual effort to apply.
In other instances, prior locking devices were of costly and complex design; were highly susceptible to malfunction particularly when exposed to various climatic conditions; were difficult and expensive to install on a loading dock; and/or they restricted or interfered with the full use of the loading dock.